A data network (network) facilitates data communication between two or more data processing systems. The data traffic from one data processing system to another passes through one or more networking devices to reach the destination.
A networking device is any device that receives data from a source and passes the data to a destination. The source and the destination can be a data processing system or another networking device. A networking device itself can be a data processing system, and conversely, a data processing system can perform the functions of a networking device.
Typically, a data packet sent from a source data processing system is handed-off through one or more networking devices before reaching a destination data processing system where the hand-off on each networking device occurs according to certain rules in the networking device. A rule for determining where a data packet goes next from a networking device in the packet's journey towards a destination data processing system is stored in the networking device.
Such a rule is called a routing rule or a next hop rule. A routing table within a networking device is one manner of storing such rules in the networking device.